Known in the art is an exhaust gas purification device designed to remove the NOx by spraying exhaust gas discharged from the engine into a bubbling tank filled with water to dissolve the NOx in the water in the bubbling tank, supplying the water dissolving the NOx into a neutralizing tank provided with a large number of electrode plates to convert the NOx contained in the water to a soluble substance by electrolytic action, and discharging the water (see Japanese Patent Publication (A) No. 2003-301714).
However, in the above mentioned exhaust gas purification device, the electrode plates are consumables. Accordingly, there is a problem in that the electrode plates must be replaced often.